Date: Tue, 30 Jun 1998 16:16:39 -0400 (EDT) From: zhihuizhang <bf20761@binghamton.edu> To: hackers <freebsd-hackers@FreeBSD.ORG> Subject: Trap types and AST Message-ID: <Pine.SOL.L3.93.980630160446.11172B-100000@bingsun2>
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I am trying to trace down how the vm_fault() gets called via trap mechanism and I find something do not understand: (1) The value of T_PAGEFLT is 12 not 14. Why trap type definitions in trap.h do not conform to the trap numbers defined in 80386 hardware terminology (one more example is T_NMI which is defined as 19 not 2). (2) The setidt() in file machdep.c set the DPL for page fault as SEL_KPL. This will prevent a normal process from handling page fault, only kernel process can. Why is the case? (this question requires the understanding of gate descriptors). (3) I come across many occurrences of AST, such as SWI_AST_MASK. Clearly, AST does not stand for the PC manufacturer here. I read in Mailing list that AST is an event. Can anyone tell me what does AST stand for and how it is used? Thanks in advance. ------------------------------------------------- Zhihui Zhang Department of Computer Science State University of New York at Binghamton Web Site: http://cs.binghamton.edu/~zzhang ------------------------------------------------- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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